Research to find ways of slowing the development of herbicide resistant weeds in the northern grain belt is making good progress.

Steve Walker of the Queensland Department of Primary Industries and Weeds Cooperative Research Centre said the work was now in the field experiment stage, following extensive industry consultation to identify herbicide resistant weeds in the grain area from Dubbo to Central Queensland.

Dr Walker said the Grains Research and Development Corporation-supported work was important because of the risks herbicide resistance posed to farming generally and particularly to cropping systems using zero tillage and limited rotation.

He said extensive consultation with farmers and agronomists in the region had shown weeds that had or were likely to develop herbicide resistance varied according to location.

The main consistency across the region was that common sowthistle and summer grasses were all rated as high risk for resistance to Group M herbicides.

He said the survey showed there were no weeds with confirmed resistance in Central Queensland, but a number of weeds were identified as having moderate to high risk of developing resistance in opportunistic cropping systems. These included sweet summer grass, barnyard grass, liverseed grass and common thistle to Group M herbicides, and parthenium weed to Group B.

"In southern Queensland seven weeds are confirmed resistant. These are wild oats (Group A), turnip weed, African turnip weed, Indian hedge mustard, common sowthistle and black bindweed (Group B), and liverseed grass (Group C).

"New weeds at most risk of developing resistance in southern Queensland are barnyard grass, liverseed grass, common sowthistle and wild oats (Group M).

"In northern and central New South Wales, seven weeds are confirmed resistant. These are wild oats and paradoxa grass (Group A), turnip weed, Indian hedge mustard, common sowthistle and charlock (Group B), and ryegrass (Group M).

"New weeds at most risk of developing resistance in northern and central New South Wales are wild oats, barnyard grass, liverseed grass, common sowthistle (Group M), ryegrass to (Group A), and black bindweed and other Brassica weeds (Group B)."

He said herbicides for wild oats control (Group A), widely used sulfonylureas like Ally and Glean (Group B), as well as glyphosate (Group M), had an important role in weed control and minimum tillage farming.

 Dr Walker said since the risk assessment, 10 long-term field experiments were established on farms in different parts of the region. 

"These experiments are testing the effectiveness of preventive strategies for weeds at risk of developing herbicide resistance for the main crop rotations. 

"More cost-effective options for managing these weeds in the long-term are being evaluated, with the focus on running down the seed-bank. This will result in paddocks with fewer weed problems in the future."

He said the industry was kept up-to-date with this research and other resistance issues in the "Northern Herbicide Resistance Reporter", published twice a year and available at the Weeds CRC website (www.weeds.crc.org.au).

The research runs for four years.